Commits

Git/Stream.fs

@@ -0,0 +1,45 @@
+namespace Git.Internals
+
+open System.IO
+
+[<RequireQualifiedAccess>]
+module internal Stream =
+
+    /// Consume the stream until and including the first instance of `stopAt`.
+    /// Return None instead if the stream is already used up; throw if we hit the end of the stream
+    /// before hitting `stopAt`.
+    let consumeTo (b : Stream) (stopAt : byte) : byte array option =
+        let rec consumeTo () : byte seq =
+            seq {
+                let b = b.ReadByte ()
+                if b < 0 then failwithf "Stream ended in the middle while consuming to '%i'." stopAt
+                if b <> int stopAt then
+                    yield byte b
+                    yield! consumeTo ()
+            }
+
+        // Read the first one to see if we can
+        let firstByte = b.ReadByte ()
+        if firstByte < 0 then None else
+
+        let firstByte = byte firstByte
+        if firstByte = stopAt then Array.empty |> Some
+        else
+            seq {
+                yield firstByte
+                yield! consumeTo ()
+            }
+            |> Seq.toArray
+            |> Some
+
+    /// Consume the first n bytes of the stream. Throw if the stream runs out first.
+    let consume (b : Stream) (n : int) : byte array =
+        let output = Array.zeroCreate<byte> n
+        let total = b.Read (output, 0, n)
+        if total <> n then failwithf "Reached the end of the stream while consuming %i bytes" n
+        output
+
+    let consumeToEnd (b : MemoryStream)  : byte array =
+        use newMs = new MemoryStream()
+        b.CopyTo(newMs)
+        newMs.ToArray ()